Amino-substituted indolin-2(3H)-ones have been prepared by the polyphosphoric acid catalyzed cyclization of mandel (o- and p-amino-substituted)anilides. 5- and 7-Pyrrolidino, piperidino, homopiperidino, N-methyl piperazino and morpholino indolin-2(3H)-ones were prepared, according to Mullock et al., J. Chem. Soc., 1970, 829.